Download antimicrobial resistance - Tayside Respiratory Research Group

Microbiology of Respiratory
Infection II
Dr Michael Lockhart
Respiratory Infections
Infections of throat and pharynx
 Infections of middle ear and sinuses
 Infections of trachea and bronchi
 Infections of the lungs

Infections of throat and
pharynx
Sore throat
 Diphtheria
 Candida/thrush
 Vincent’s angina

Infections of throat and
pharynx

Diagnosis:
–
Well taken throat swab
SORE THROAT
Sore throat

VAST MAJORITY (OVER TWO THIRDS)
- VIRAL
–
DO NOT NEED ANTIBIOTICS
Bacterial sore throat

The most common BACTERIAL cause is
Streptococcus pyogenes (also known as
Group A streptococci)

Clinical: Acute follicular tonsillitis

Treatment:Penicillin
Streptococcus pyogenes
Streptococcal sore throat

Acute complications:
–
–
–
Peritonsillar abscess (quinsy)
Sinusitis/ otitis media
Scarlet fever
QUINSY (PERITONSILLAR
ABSCESS)
Streptococcal sore throat

Late complications
–
Rheumatic fever
3
weeks post sore throat
 fever, arthritis and pancarditis
–
Glomerulonephritis
 1-3
weeks post sore throat
 haematuria, albuminuria and oedema
Diphtheria

Corynebacterium diphtheriae

Clinical: Severe sore throat with a grey
white membrane across the pharynx. The
organism produces a potent exotoxin which
is cardiotoxic and neurotoxic.
DIPHTHERIA
DIPHTHERIA
Diphtheria

Epidemiology : Rare, but increased in certain parts
of the world eg Russia

Treatment: Antitoxin and Supportive and
Penicillin/erythromycin
Candida/Thrush

Candida albicans

Clinical: White patches on red, raw mucous
membranes in throat/ mouth

Cause: endogenous

Treatment: Nystatin
ORAL THRUSH
Vincent’s angina

Mixture of organisms (Borrelia vincenti and
Fusobacterium sp.)

Clinical:Foul smelling mouth and throat
ulcers

Treatment: penicillin
VINCENT’S ANGINA
Respiratory Infections
Infections of throat and pharynx
 Infections of middle ear and sinuses
 Infections of trachea and bronchi
 Infections of the lungs

EAR
OTITIS MEDIA
Infections of middle ear and
sinuses
Often viral with bacterial secondary
infection
 Most common bacteria: Haemophilus
influenzae, Streptococcus pneumoniae and
Streptococcus pyogenes.
 Treat: Amoxycillin

Respiratory Infections
Infections of throat and pharynx
 Infections of middle ear and sinuses
 Infections of trachea and bronchi
 Infections of the lungs

Infections of trachea and
bronchi
Acute epiglottitis
 Acute exacerbations of COPD
 Cystic fibrosis
 Pertussis (whooping cough)

Acute epiglottitis
Haemophilus influenzae
 Clinical: severe croup in children aged 2-7
years, may progress to respiratory
obstruction and death.

EPIGLOTTITIS
EPIGLOTTITIS
Acute epiglottitis

Microbiology of Haemophilus influenzae
–
–
–
–
Habitat - upper respiratory tract
Microscopy- small gram negative bacillus
Culture - Chocolate agar -small translucent
colonies
Identify - “X and V test”; H influenzae requires
both factors X and V to grow.
Haemophilus influenzae
Acute epiglottitis

Diagnosis: blood culture (?throat swab)

Treatment: ITU and ceftriaxone
COPD

Acute exacerbations of COPD.
–
Exacerbations of this chronic condition are
often associated with bacterial infection.
Acute exacerbations of COPD
Often follow viral infection, or fall in
atmospheric temperature with increase in
humidity (often in winter)
 Clinical: Patients present with increased
breathlessness. The volume and purulence
of sputum is increased.

Acute exacerbations of COPD

The most common organisms associated
are:
–
–
–

Haemophilus influenzae
Streptococcus pneumoniae
Moraxella catarrhalis
NB All three organisms are present in
normal upper respiratory tract flora.
Acute exacerbations of COPD




Treatment:
Give antibiotics if ↑sputum purulence. If no ↑sputum
purulence then antibiotics not needed unless consolidation
on CXR or signs of pneumonia.
1ST LINE Amoxicillin 500mg tds 2ND LINE Doxycycline
200mg on day 1 then 100mg daily (5 days)
With time becomes increasingly difficult to treat, due to
acquisition of more resistant organisms.
Cystic fibrosis

Inherited defect
–
leads to abnormally viscid mucus which blocks
tubular structures in many different organs
including the lungs.
Cystic fibrosis
Chronic respiratory infection is a major
problem.
 Causal bacteria:

–
–
–
Staphylococcus aureus and Haemophilus
influenzae
Pseudomonas aeruginosa
Burkholderia cepacia
Pertussis (whooping cough)
Bordetella pertussis
 Clinical: Acute tracheobronchitis

–
–
cold like symptoms for two weeks
paroxysmal coughing (2 weeks)
 repeated
violent exhalations with severe inspiratory
whoop, vomiting common
–
residual cough for month or more
Pertussis (whooping cough)

Diagnosis:
–
–
–


pernasal swab (charcoal blood agar/ Bordet-Gengou
medium)
serology
clinical ( by the stage of paroxysmal coughing organism
numbers much reduced)
Treatment: most effective in the first 10 days of
illness, also reduces spread to susceptible contacts
Vaccination
Pernasal swab
Respiratory Infections
Infections of throat and pharynx
 Infections of middle ear and sinuses
 Infections of trachea and bronchi
 Infections of the lungs

Infections of the lungs
Community acquired pneumonia
 Nosocomial pneumonia
 Legionnaires disease
 Pneumocysitis carinii pneumonia (PCP)
 Fungal chest infection
 Tuberculosis

Community acquired
pneumonia
Clinical: cough, sputum production,
dyspnoea, fever.
 Chest x-ray with infiltrates.
 Acquired in the community

Community acquired
pneumonia

Causative organisms:
–
–
–
–
–
Streptococcus pneumoniae
Atypicals/viruses
Staphylococcus aureus
Other bacteria
Haemophilus influenzae
70%
20%
4%
1%
5%
Community acquired
pneumonia

Streptococcus pneumoniae
–
Microbiology:
 Microscopy
- gram positive cocci
 Culture - Alpha haemolytic colonies, typically
“draughtsmen” ie with sunken centre.
 Identify - “Optochin” sensitive
–
Treatment - generally penicillin sensitive
Streptococcus pneumoniae
Lobar pneumonia
Community acquired
pneumonia
“Atypicals” - old term for pneumonias not
attributable to any of the common bacterial
causes of pneumonia.
 Refer to Dr McIntyre’s talk

Community acquired
pneumonia

Treatment , follow the Tayside Critical Care
Pathway for the Management of
Community-Acquired Pneumonia
CURB65 SCORE
3 OR MORE
(SEVERE)
ANTIBIOTICS: SEVERE
ALL SHOULD INITIALLY RECEIVE:
IV CO-AMOXICLAV 1.2g x3/day PLUS IV
CLARITHROMYCIN 500mg x2/day or PO
DOXYCYCLINE 100mg x2/day
(PENICILLIN ALLERGY:
IV Levofloxacin 500mg2/day)
 Step down to oral doxycycline 100mg x 2/day in
all patients
ALL SHOULD HAVE: Paired serology, throat
swab/gargle for virology PCR, urinary legionella
antigen tests
Treat for at least 10 days (IV/oral)
Nosocomial pneumonia
= hospital acquired pneumonia
 Predisposing factors:

–
–
–
–
–
Intubation
Intensive care unit
Antibiotics
Surgery
Immunosuppression
Nosocomial pneumonia

Organisms -60% gram negative organisms :
–
–

includes Pseudomonas aeruginosa, and Coliforms
(such as E.coli, Klebsiella sp)
If aspiration pneumonia anaerobes may be involved
Treatment
–
Severe IV Amoxicillin + Metronidazole + Gentamicin

–
Step down to Coamoxiclav PO 7-10 days total
Non severe Amoxicillin + Metronidazole for 7 days
Legionnaires disease
Legionella pneumophila
 Clinical:

–

flu like illness which may progress to a severe
pneumonia, with mental confusion, acute renal
failure and GI symptoms.
Epidemiology
–
often associated with travel, usually associated
with water.
Legionnaires disease
Diagnosis: Legionella urinary antigen/
Serology
 Treatment:

–
–
Erythromycin/clarythromycin
Fluoroquinolones
Pneumocysitis carinii
pneumonia (PCP)
A cause of pneumonia in patients with
AIDS
 Diagnosis: Bronchioalvelar lavage (BAL)
or induced sputum and identification of
cysts.
 Treatment: Cotrimoxazole, pentamidine.

Fungal chest infection


Aspergillus fumigatus
Clinical: Causes severe pneumonia/systemic
infection in the severely immunocompromised.
–


Or aspergilloma
Diagnosis : Culture
Treatment : iv Amphotereicin B
ASPERGILLOMA
TUBERCULOSIS
Mycobacterium tuberculosis
 Acid Alcohol Fast Bacilli
 Bread crumb like growth on special
medium, after prolonged (up to 3 months)
incubation

Acid and Alcohol Fast Bacilli
(AAFB)
Growing Tuberculosis
Tuberculosis

For more detailed information see Dr
Winters Lecture
Infections in lungs
General diagnostic points
Infections of the lungs Diagnosis

Isolation of causal pathogen
–
–
Sputum NB Quality of sputum sample
important
Blood culture (organism in blood of one third
of patients with pneumonia)
Infections of the lungs Diagnosis

Detection of bacterial antigen
–
–

eg Legionella urinary antigen
Direct immunofluorescence for PCP
Serology
–
eg Legionella serology
Immunisation

UK guidance is summarised in a document
called “The Green Book” available online
at:
–
http://www.dh.gov.uk/PolicyAndGuidance/Heal
thAndSocialCareTopics/GreenBook/fs/en
Pneumococcal immunisation

Pneumococcal polysaccharide vaccine
covers 23 different capsule types
–

Efficacy – 50-70% reduction of bacteremia risk
Pneumococcal conjugate vaccine covers 7
different capsular types – common
childhood strains
–
Efficacy – 97% protection
Pneumococcal immunisation

Indications
–
–
–
All those aged 65 years and over
Childhood immunisation schedule
Risk groups
 No
spleen
 Various chronic diseases including COPD
 Immunosuppressed
 Patients with CSF shunts
Hib
Invasive Haemophilus infection caused
most commonly by Type b capsular strains
(Hib).
 Conjugate vaccine offered to all children
less than 1, and all asplenic individuals
 Highly effective

Pertussis immunisation
Acellular vaccine – 5 purified pertussis
components
 Given as part of the childhood
immunisation schedule

Immunisation for Tuberculosis
Live attenuated strain of Mycobacterium
bovis
 UK efficacy of 70% in protecting against
TB
 Risk based approach to identify those who
receive the vaccine

Community acquired
pneumonia

Causative organisms:
–
–
–
–
–
Streptococcus pneumoniae
Atypicals/viruses
Staphylococcus aureus
Other bacteria
Haemophilus influenzae
70%
20%
4%
1%
5%